What should I do if I overstayed my B1/B2 visa and won DV visa?

You may be eligible for consular processing of your DV lottery visa if you were really an overstay for less than 1 year and you have since been out of the country for 3 years.

By overstaying your B1/B2 visa, you have put yourself in a legal bind. Ideally, if you are in the US and entered legally, you should be able to apply for adjustment of status after you won the DV. However, in order to apply for adjustment of status, you normally must be in legal status to apply. Unless you qualify for one of the few exceptions, adjustment of status does not appear to be an option for you. The other way to get your residency is to return to your home country to apply for an immigrant visa. However, by overstaying your B1/B2 status by 11 months, you have become subject to the 3-year bar under INA sec. 212(a)(9)(B)(i)(I), which makes you inadmissible to the US for 3 years unless you apply for and are granted a waiver on form I-601. To qualify for the waiver, you must establish extreme hardship to a spouse and/or parent(s) who are US citizens or residents.

Better see an immigration attorney, you have several issues. You may not be able to get the green card.